Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Beta-Leu5-endorphin, a relative of "normal" beta-endorphin in which leucine is substituted for methionine at position 5 of the latter, has previously been found in high concentrations in the dialysate of schizophrenics. Its removal from plasma by means of hemodialysis has been claimed to relive the symptoms of schizophrenia. Using a highly sensitive radioimmunoassay of equal sensitivity to beta-endorphin and beta-leu5-endorphin, we have compared the plasma immunoreactivity of three schizophrenic patients befofe and after performance of their first session of membrane hemoperfusion. As compared to normal subjects, plasma beta-endorphin-like immunoreactivity was not greatly elevated in the schizophrenic patients before hemoperfusion.However, instead of the expected decrease, a consistent increase in the plasma levels of immunoreactive beta-endorphin was detected after hemoperfusion. In vitro experiments in which two different membranes and hemodialysis as well as hemoperfusion were used, revealed that synthetic beta-leu5-endorphin (and beta-endorphin) from human plasma was not cleared with any of these methods. This finding is inconsistent with the hypothesis that the claimed therapeutic effects of hemodialysis in schizophrenics are due to the removal of a beta-endorphin-like material from the plasma. Consequently, it seems to be unprobable that high concentrations of beta-leu5-endorphin occur in the dialysate or ultrafiltrate of schizophrenics.
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PMID:Endorphins in schizophrenia: hemodialysis/hemoperfusion are ineffective in clearing beta-Leu5-endorphin and beta-endorphin from human plasma. 53 84

The release of melanocyte-stimulating hormone (MSH) into the medium during incubation and the pituitary tissue content of MSH were measured separately using pituitary glands collected from rats at various stages of the oestrous cycle. The MSH was measured by a biological assay using a synthetic alpha-MSH as standard. The release of MSH was maximal during thepro-oestrous phase and MSH content of the pituitary gland was highest during dioestrus. The influences of the tripeptide Pro-Leu-Gly-NH2, which inhibits MSH secretion in vivo, and of progesterone on the release of MSH in vitro were studied with tissue collected at various phases of the oestrous cycle. Pro-Leu-Gly-NH2 was effective in inhibiting MSH release both at pro-oestrus and oestrus but not at dioestrus. Progesterone overcame this inhibition.
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PMID:Differences in the release of melanocyte-stimulating hormone in vitro by rat pituitary glands collected at various times during the oestrous cycle. 56 39

1 A method is described for the rapid extraction of opioid peptides from the brain and other tissues. The method is based on acid extraction of tissues followed by adsorption of the extract onto Amberlite XAD-2 resin. Elution with methanol separates the enkephalins and alpha-endorphin from beta-endorphin.2 Over 90% of the opioid peptide activity isolated from brain and gut of several species by our method was due to methionine- and leucine-enkephalin. In contrast, the major opioid peptide activity recovered from the pituitary was due to peptides of much greater mol. wt. than the enkephalins.3 An opioid peptide with properties unlike those of the known endorphins or enkephalins was present in brain extracts. This peptide, termed epsilon-endorphin, has an apparent mol. wt. of 700 to 1200; it constituted between 5 to 10% of the total opioid activity in our extracts.4 A differential assay of methionine- and leucine-enkephalin was made either by destroying methionine-enkephalin activity with cyanogen bromide or by separating the peptides by thin layer chromatography.5 The ratio of methionine-enkephalin to leucine-enkephalin varied greatly in different brain regions. The highest proportions of leucine-enkephalin were found in the cerebral cortex and hippocampus.6 Formaldehyde perfusion and fixation of the brain in vivo had no significant effect on the brain content of enkephalin, indicating that proteolytic breakdown is not a major problem in the extraction of these peptides.7 It is suggested that the enkephalins may have a neurotransmitter role in both brain and peripheral tissues and that methionine- and leucine-enkephalin may subserve separate neuronal functions.
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PMID:The distribution of methionine-enkephalin and leucine-enkephalin in the brain and peripheral tissues. 59 68

Beta-Endorphin (0.9--2.0 nmol), morphine (11--250 nmol) and D-ala2-met-enkephalinamide (17--33 nmol) administered intracisternally produced preferential vasodepressor responses and bradycardia. Leu- (1.8--180 nmol), met-enkephalin (17--520 nmol) and alpha-endorphin (5.7--57 nmol) administered in the same way produced preferential vasopressor effects and the latter two peptides also produced bradycardia. Results obtained with naloxone (300 nmol) given intracisternally indicate that the pressor and depressor actions as well as the bradycardia are mediated through opiate receptors. The results indicate that opioid peptides may be involved in central cardiovascular control.
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PMID:Cardiovascular effects of morphine and opioid peptides following intracisternal administration in chloralose-anesthetized rats. 63 59

The opiate agonist potency of thirteen synthetic enkephalin pentapeptides has been examined on the electrically stimulated guinea pig ileum and mouse vas deferens preparations in comparison with methionine and leucine enkephalins, beta-endorphin and normorphine. Their antagonism by naloxone (Ke) was also assessed on each preparation. Our findings are compatible with, and are discussed in the context of, the hypothesis that these preparations possess at least two populations of receptors.
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PMID:In vitro profile of some opioid pentapeptide analogues. 65 47

Using naloxone as the antagonist, a comparison of pA2 values obtained from the guinea pig ileal longitudinal muscle preparation revealed that both leucine (leu-) enkephalin and methionine (met-) enkephalin can be classified as pure narcotic agonists with pA2 values similar to that of morphine but different from that of nalorphine. In addition, cross tolerance to both met- and leu-enkephal in could be demonstrated on an ileal strip made tolerant to morphine by implantation of morphine pellets to a guinea pig for 72 hours. Pretreatment of a naive muscle strip to three increasing concentrations of leu-enkephalin was found to markedly decrease the IC50 of morphine and to sensitize the ileal strip to naloxone as was evidenced by an increase in the morphine-naloxone pA2 value. Met-enkephalin or morphine pretreatment had no effect on subsequent morphine IC50 determinations but similarly increased the morphine-naloxone pA2 value. These results suggest that although both leu- and met-enkephalin may be classified as pure narcotic agonists, their interaction with morphine on the ileal strip is markedly different. Leu-enkephalin may be an important physiological modulator of narcotic efficacy.
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PMID:Characterization of leucine and methionine enkephalin and their interaction with morphine on the guinea pig ileal longitudinal muscle. 70 20

The electrically-evoked contractions of the rat vas deferens were selectively inhibited by beta-endorphin, the preparation being much less sensitive to enkephalins and narcotic analgesic drugs. However, introduction of D-Ala in position 2 of [Leu]-enkephalin enhanced the activity of the opioid peptide to the order of that of beta-endorphin. It is concluded that the rat vas deferens preparation constitutes a specific bioassay for endogenous opioid peptides and related compounds.
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PMID:Rat vas deferens: a specific bioassay for endogenous opioid peptides. 71 30

A number of questions remain unsettled about the release of melanocyte-stimulating hormone (MSH) and about its function. Even though relatively few investigators are studying this area, some generalities have emerged during the last 10 years. It now seems that release of MSH from the pituitary is inhibited by a substance present in the hypothalamus. The structure of this physiologic inhibitor of MSH release may still not be considered an established entity but there is evidence for additional mechanisms capable of exerting a fine control on the release of MSH. Contrary to some opinions, the release of MSH does not always occur together with the release of ACTH, and the release of the two hormones can be dissociated in several laboratory and clinical situations. In addition, many studies have shown that the pituitary peptide, MSH, exerts behavioral and electroencephalographic effects in both the rat and man. The hypothalamic peptide Pro-Leu-Gly-NH2 (MIF-I) also has direct effects on the central nervous system that may include alleviation of the symptoms of Parkinson's disease.
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PMID:Some questions related to melanocyte-stimulating hormone. 96 14

Melanin was measured in various parts of the rat brain by a spectrophotofluorometric assay. This method could detect natural, Sepia melanin as well as melanin synthesized from L-DOPA. Contrary to published expectations of other investigators, measurable amounts of melanin were found in the brain of albino as well as pigmented rats. The highest concentrations of melanin occurred in the pons-medulla and midbrain, but all regions within the blood-brain barrier contained greater concentrations than samples from many other tissues in the body. No significant change in the melanin content was found after various endocrine manipulations such as removal of the pituitary, pineal, adrenals, thyroid, testes, or ovaries, exposure to constant illumination or darkness, and daily injection for 5 weeks of alpha-MSH, Pro-Leu-Gly-NH2 (MIF-I) or melatonin. As expected, retinal tissue from black-hooded rats contained extremely high levels of melanin whereas that from albino rats contained no melanin. It is thought that the presence of melanin in the brain of albino and pigmented rats may have a function which is still unknown.
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PMID:Melanin in the rat brain. 102 Dec 12

Human placental villus tissue contains opioid receptors and peptides. Kappa opioid receptors (the only type present in this tissue) were purified with retention of their binding properties. The purified kappa receptor is a glycoprotein with an apparent molecular weight of 63,000. Two opioid receptor mediated functions were identified in trophoblast tissue, namely regulation of acetylcholine and hormonal (human chorionic gonadotrophin and human placental lactogen) release. Placental content of kappa receptors increases with gestational age. Term placental content of kappa receptors correlates with route of delivery (higher in those abdominally obtained). Opioid use and/or abuse during pregnancy affects placental receptor content at delivery, as well as its mediated functions. Opioid peptides identified in placental extracts were beta-endorphin, methionine enkephalin, leucine enkephalin and dynorphins 1-8 and 1-13. Dynorphin 1-8 seem to be the predominant opioid peptide present in placental villus tissue.
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PMID:Properties and functions of human placental opioid system. 130 34


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